1.

Abbreviation for "I Love You" in net and SMS use in Chinese speaking world. It is an example of extensive use of numerical digits for their similar pronunciation of daily expressions in Chinese. In this case, 5 means "I", 2 means "love", 0 means "you".

Peter sent SMS to his girlfriend Kate: Still in meeting, 520

2.

T-Town, Tucson, AZ. From the west to the east.

Na fuck that, I am from the 520 Bitch

See 520, tucson, tbk, bloodz, blood

3.

The holiday similar to 420, but instead of smoking marajuana to celebrate this is the national pill popping day. Stoners have a holiday now pill poppers do too.

"Dude i can't wait till 520. I'm gonna pop some Valium.

See 520, pills

4.

Slang term referring to Marijuana. Probably derived from police code for same.